The author engages in his thesis in change of thermal conductivity in wood composite as a result of burning. Gradual “carbonization” of the surface layers of the wood based materials occurs during the process of burning. Charred layer have diferent thermal-technical characteristics than basic material, it influences the heat transfer through the layers of material. In the first part he has focused on basics thermodynamics, include heat transfer processes mainly conductivity. In following chapter he has focused on wood and his biological, chemist, physical wood characteristics. Furthermore, he explores the thermal degradation of wood and char layer formation in burning processes. In forth part he has focused on agglomerated materials a process for the production of adhesive used as a binder in composite wood. In practical part he describes measurement of thermal conductivity OSB and QSB plate in a thermally insulated chamber. In last chapter he has compared depandance between thickness of the char layer and the heat transfer efficiency in the wood. The measured values show a change in the thermal conductivity due to charring. The higher rate of charring reduces the thermal conductivity in materials-based products.